With the spread of network systems including a plurality of networks, the number of households that connect personal computers (PC) and information processors such as home information appliances with home networks at home is increasing.
As a method of easily using the information processor connected with home network, a method called UPnP (Universal Plug and Play) is generally used.
UPnP is a method of automatically discovering and controlling information processors through the network, and the standardization work is done by the UPnP forum (http://www.upnp.org).
UPnP identifies what type of device the information processor in the home network is and what kind of service it provides by transmitting a definition file compliant with XML (Extensible Markup Language) that defines things such as what type of device the information processor in the home network is and what kind of service it provides.
By using this, a mechanism to use information (e.g., content) including contents from other networks through the home network is realized.
As one type of UPnP, there is a standard called UPnP AV Media Server. By using a technology compliant with this standard, a method for communicating the content information among a plurality of networks and a method of delivering the content information through home networks are defined.
Explaining in more detail, recently, it has become more popular to watch videos such as private videos and images taken with a digital camera not on the information processor where the images are accumulated but on another information processor through the home network.
At the same time, a remote access system to use the content information accumulated in the information processor at home by accessing it from outside through the internet has also increased in use.
In addition, the use of services such as video streaming service has been spread. A service to deliver video contents from an information processor such as a server connected with the internet, receive the information such as contents by using a set-top box to watch the contents is also available.
FIG. 1 is a schematic drawing showing how information is delivered through networks in a general network system. FIG. 2 is a schematic drawing showing a conventional first method to make the information delivered through networks available in home networks. FIG. 3 is a schematic drawing showing a conventional second method to make the above-mentioned information available in home networks.
In the network system shown in FIG. 1, an information processor 210 (for example, a server) of the delivery source is connected with an external network (for example, internet) 200.
On the other hand, an information processor (for example, personal computer (PC)) 310 of the delivery destination and another information processor (for example, player) 320 of the delivery destination are connected with a home network (internal network) 300.
In addition, a gateway device 100 to control a plurality of information processors (the information processor 310 of the delivery destination and another information processor 320 here) is connected to the external network 200 and the home network 300.
However, here, it is assumed that it is wanted to deliver information such as contents through the external network 200 and home network 300, from the information processor 210 of the delivery source in the external network to the information processors (the information processor 310 of the delivery destination and another information processor 320) in the home network 300.
In the network system in FIG. 1, to deliver the content information from the information processor of the delivery source in the external network or from the information processor in the home network of another household, to the information processor in the home network of one household, it is necessary that one information processor of the delivery destination (for example, another information processor 320 of the delivery destination) be connected with the home network. Also, the power supply of the information processor is turned on (that is, it enters the service providing state in which service to receive the information such as contents can be supplied).
Conversely speaking, when the power supply of the information processor of the delivery destination turns off, because it is impossible for the information processor of the delivery destination to receive the content information, an inconvenient situation in which the information cannot be effectively used in the household of the delivery destination occurs.
As a first method to solve such an inconvenient situation and make it possible to use the content information in the home network, as shown in FIG. 2, a method has been used in which the information is received first by an information processor (for example, information processor 310 of the delivery destination) that is different from the intended information processor (for example, information processor 320 of the delivery destination), and the information is later received by the information processor that uses the information through the home network.
Explaining in more detail, as the information processor of the delivery destination, the 24-hour operating information processor 310 (for example, personal computer) is prepared as a server, and this information processor 310 temporarily receives and acquires the information such as contents delivered from the information processor 210 of the delivery destination.
In this case, the information processor 210 of the delivery source has to deliver the information to the information processor 310 that can always receive the information (Step 1).
Next, after turning on the power supply of another information processor 320 (for example, player) of the delivery destination and starting the information processor 320, the information is downloaded from the 24-hour operating information processor 310, which makes the information such as contents available in the home network (Step 2).
On the other hand, as the conventional second method to make the information available on the home network, for example, as shown in FIG. 3, a method in which the gateway device 100 alternatively provides service by using the device information and service information of the information processors (information processor 310 of the delivery destination and another information processor 320) of the delivery destination in the home network and control the power supply state of the information processor.
This method provides access from an external network regardless of the power supply state of the information processor of the delivery destination by turning on the power supply of the information processor of the delivery destination with the gateway device 100 if necessary.
Explaining in more detail, the 24-hour operating gateway device 100 is prepared between the information processor 210 of the delivery source and the information processor of the delivery destination (Step 1).
Next, when the information such as contents is delivered from the information processor 210 of the delivery source, the gateway device 100 checks the information of the delivery destination and turns on the power supply of the information processor of the delivery destination (for example, the information processor 310 of the delivery destination) (Step 2).
In addition, after the power supply of the information processor of the delivery destination turns on, the gateway device 100 delivers the information such as contents to the information processor of the delivery destination.
Here, when the information such as contents is delivered, by changing the state of the power supply of the information processor that receives the information, the information such as contents can be used in the home network (Step 3).
However, in the first method in above-mentioned FIG. 2, because one information processor (24-hour operating information processor) functioning as a server receives and controls the information of all the contents, the information processor can run out of storage capacity. Also, the information delivery side as a server sometimes cannot determine to which information processor the information should be delivered.
On the other hand, in the second method in above-mentioned FIG. 3, the gateway device that controls the information processor of the delivery destination in the home network receives an access from an external network once, then it identifies which information processor to deliver to.
However, in this method, when the delivery frequency of the information such as contents becomes high depending on the service use state, change between on and off of the power supply of the information processor of the delivery destination is repeated and a problem of increasing the power consumption of the information processor occurs.
In addition, when the state of power supply of the information processor of the delivery destination cannot change (for example, the information processor is not connected with networks temporarily), the information such as contents cannot be delivered.
Here, for reference, as related art document with regard to the above-mentioned conventional method, Japanese Laid-open Patent Application No. 2005-73142 is indicated.
Patent document 1 (Japanese Laid-open Patent Publication No. 2005-73142), in a wireless AV station 101, discloses a data transmitter that controls the supply of power supply V4 to a communication section 313 that functions as a router and the supply of power supplies V1 and V3 to AV buses 211 and 215 independently, further controls the supply of the power supply V1 to the AV bus 211 that receives broadcast data and the supply of the power supply V3 to the AV bus 215 that receives content data from an external device independently.
Because such configuration, depending on the service use state of each AV bus 211 and 215, can turn on and off the power supply of the AV bus 211 and the power supply of the AV bus 215 respectively, power can be supplied to only necessary buses.
However, Patent document 1 does not refer to a concrete method to solve the problem that power consumption increases due to the repetition of changing between on and off of the power supply of such as a communication section and AV bus when the frequency of using services such as communication service, broadcast program receiving service and contents data receiving service at all.
As a result, Patent document 1 cannot solve such a problem that occurs when the information such as contents is delivered to the information processor of the delivery destination through the network by the above-mentioned conventional second method.